Approximately 500,000 BC: Microbial life is continuing to survive in the crust of Mars; Circa 2000 AD Earth-based radioactive carbon dating will be accurate to around this time

Bits of Mars blasted off the planet now by cosmic impacts will eventually find their way to Earth (and be labeled meteorites EETA 79001 and ALH 84001), and display strong evidence for continuing widespread survival on Mars of at least microscopic organisms.